shallow well pump not pumping

I have a Pacific Hydrostar Shallow well pump - model number 47906. I use it for a hydraulic boat lift. When the lift is low the pump will turn on and pump for about 5 seconds and then it shuts off and will not come on again. I have a water hose pipe also attached to the pump that goes to a hose. If I turn on the hose the pump will come on for another few seconds and then stop again. If I try enough different ways with the hose I can eventually get the pump to come on enough times to raise the boat. Once it gets to a certain level then the pump will take over, cycle on and off several times on its own and finish the job.

The pump was pretty cheap, but it is similar to the one I had for several years previously that worked fine. In reading through some of the other posts I am thinking this might be a pressur eissue, but I'm not sure. Any help would be gretly appreciated. Jeff

Thanks Gary for your response. I guess I need to be clearer. The pump itself doesn't shut off - the switch stays in the on position. But when I open the lever on the boat lift that lets in the water to the lift, it pumps water for a few seconds and then stops. Sometimes it will pump again about 30-45 seconds later for another few seconds. It seems to have gotten worse as the lake as lowered and the boat has to be lifted from a different angle. I am thinking that maybe the pump is not putting out enough pressure to lift the boat. Is that possible?

If the pump shuts off when it shouldn't, you have any of the problems I mentioned before. You can't get water (pressure) if the pump doesn't run right? So you figure out what prevents the pump from running when it should. maybe it is the lower water level in the lake.

Once it gets to a certain level then the pump will take over, cycle on and off several times on its own and finish the job.
Jeff

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It could be any of the things Gary mentioned. However, I think it is the overload in the motor tripping, then reseting in a little bit, and trying again. Runing wide open with no pressure makes the pump pull the highest load and trip the overload. Holding back some pressure with the hose actually decreases the load but, causes cycling. If it has always been cycling on and off to work properly (not good), you probably have destroyed the motor and it trips the overload when running max flow.

Gary - thank you. You mentioned that it could be a problem with the 'wet end binding up'. Can you be more specific as to what that means?

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Pumps come in 2 parts; the motor rated in hp and the wet end rated in gpm. The wet end is the part the motor shaft spins and the water line(s) are attached to.

I don't know how water lift lifts a boat out of the lake unless you pump water into a counterweight to lift the boat and then drain that water out to lower the boat.

If so and you can't get the pump to suck water as high as the pump is above the water, you need to raise the lake water level or lower the pump closer to the lake level, or use another pump that will suck water from that depth and deliver it where it needs to go, right?

It sounds to me as if the pump motor is overheating and the thermal overload is shutting it off so the motor doesn't burn up. If it has never done the lifting right since you bought it, it sounds as if it isn't the same hp or size (gpm etc.) as the original pump was.

Thanks Gary - ok...I checked the intake and everything seems to be working well. When the pump is on there is a strong suction and there is nothing blocking the water. I also have a hose hooked up to the pump. When I just turn the hose on (no boat lift operating), the pump cycles on and off. When I count, it seems like it will come on for approx. 4 seconds and then shut off for the same amount of time and then turn on again...every 4 seconds or so. The water comes out of the hose the entire time, but the pressure goes up when the pump is on and down when it shuts off. What does that mean? I checked the pressure gauge and it stays constant throughout.